Changing epidemiology of nontuberculous mycobacterial lung disease in South Korea.

Abstract

OBJECTIVES

Pulmonary nontuberculous mycobacteria (NTM) are increasing worldwide, but data from
regions with an intermediate tuberculosis (TB) burden are insufficient, and the reason
for the changing epidemiology of NTM lung disease is unclear. We investigated the
trends of NTM lung disease at a tertiary hospital in Korea and evaluated the contribution
of liquid culture systems.

METHODS

We conducted a retrospective observational study of mycobacterial cultures of respiratory
specimens from 26,793 patients at Severance Hospital in South Korea from January 2006
to December 2010.

RESULTS

The recovery percent of Mycobacterium tuberculosis isolates was 5.9% in 2006 and 7.1%
in 2010, and the recovery percent of NTM isolates was 2.0% in 2006 and 6.3% in 2010.
The annual percent of NTM isolation has increased steadily every year (p for trend
< 0.001), and the proportion of patients from whom NTM was isolated increased from
21.4% in 2006 to 55.0% in 2010 (p for trend < 0.001). The incidence (per 100,000 inpatients
and outpatients) of patients with NTM lung disease was 1.82 in 2006 and increased
to 4.38 in 2010 (p < 0.001). Although the proportion of positive cultures in liquid
medium only was higher for NTM than for M. tuberculosis (p < 0.001), the NTM recovery
rate has increased in solid medium culture systems.

CONCLUSIONS

The incidence of patients with NTM isolated from respiratory specimens and NTM lung
disease increased from 2006 to 2010 in South Korea, a region with an intermediate
TB burden.